Bead apex rubber-forming method, and bead apex rubber-forming device

ABSTRACT

The present invention forms bead apex rubber with good precision on the outer circumferential surface of the bead core. A molding process, in which unvulcanized rubber is made to flow into a bead apex molding chamber that is surrounded by surfaces that include the outer circumferential surface of a circular bead core and the bead apex rubber is formed directly on the outer circumferential surface of the bead core that is rotating around the core axis, is provided. The molding process comprises: a tip forming step that forms the leading end of the bead apex rubber; a middle section forming step that sequentially forms the bead apex rubber to be continuous with the leading end; and a joining step to join the back end and the leading end of the bead apex rubber by inflowing the unvulcanized rubber therebetween.

TECHNICAL FIELD

The present invention relates to a bead apex rubber forming method and abead apex rubber-forming device capable of forming accurately bead apexrubber on an outer circumferential surface of a bead core.

BACKGROUND ART

As shown in FIG. 11(A) schematically, a bead portion (a) of a pneumatictire is provided with an annular bead core (c) made of a hard steel wireand the like to fix both ends of the carcass (b) securely and to preventfrom dropping-off of a rim. The radially outer circumferential surfaceof the bead core (c) is provided with bead apex rubber (d) having atriangle shape in cross-section to improve bead durability and steeringstability and the like. This bead apex rubber (d) is gone into a tiremanufacturing line as a bead apex rubber-core joint body jointedintegrally with the bead core (c) in advance (hereinafter called a “corejoint body”).

As the forming method of the core joint body, heretofore, as shown inFIG. 11(B), the bead apex rubber (d) having the triangle shape incross-section extruded and formed with a rubber extruder is wrapped onceon the outer circumferential surface of the bead core (c). Then bothwrapping ends of tip portion and back-end portion are butted andjointed. At this time, the bead apex rubber (d) having a hightemperature just after molding is soft and deformable. Therefore, tofeed the bead apex rubber (d) just after molding to the bead core is noteasy. It needs to once cool down after molding.

However, the cooling deteriorates adherence property of the bead apexrubber (d). In consequence, the lack of adhesion makes it easier to fallaway the bead apex rubber (d) from the bead core (c) (see FIG. 12(A)).The cross-sectional shape deforms such as shrinking and curling of thebead apex rubber (d) in the width direction (see FIG. 12(B)). In theevent of the severe curl, a tip portion (d1) and a back-end portion (d2)cannot be jointed. when the cross-sectional height of the bead apexrubber (d) is large, the bead apex rubber (d) falls due to the curl andit makes difficult to form the core joint body. Also there is problemsthat the joint portion drops off between the tip portion (d1) and theback-end portion (d2) owing to adhesion insufficiency (see FIG. 12(C)),and a gap (f) between the tip portion (d1) and the back-end portion (d2)(see FIG. 12(D)) and overlapping (g) between the tip portion (d1) andthe back-end portion (d2) (see FIG. 12(E)) causes weight unbalance.

As a conventional device of the bead apex rubber to the bead core isknown as the following Patent Documents 1 and 2.

BACKGROUND OF THE INVENTION Patent Documents

Patent Document 1: Japanese Unexamined Patent Application PublicationNo. H10-291261

Patent Document 1: Japanese Unexamined Patent Application PublicationNo. 2004-202960 GENERAL DESCRIPTION OF THE INVENTION Problems to beResolved by the Invention

It is an object of the present invention to provide the bead apex rubberforming method and a bead apex rubber-forming device capable of keepinga high adhesion strength between the bead apex rubber and the bead core,and of preventing the deformation caused by the shrinking; moreover, thebead apex rubber is substantially formed in a joint-less form, theproblems of the weight unbalance caused by the occurrence of the gap andoverlapping in the joint portion and the adhesion dropping-off in jointportion can be prevented.

Means of Solving the Problems

In the invention according to claim 1, a bead apex rubber forming methodforms the bead apex rubber continuously in a full circle on an outercircumferential surface of the annular bead core having a core axis. themethod comprises a molding process to form the bead apex rubberintegrally on the outer circumferential surface of the bead corerotating around the core axis by flowing unvulcanized rubber from arubber inflow port positioned in a first inner wall surface of a moldinghead into a bead apex molding chamber. The bead apex molding chamber issurrounded by the outer circumferential surface of the bead core, afirst inner wall surface of the molding head on one side of the coreaxis direction, and a second inner wall surface of the molding head onthe other side of the core axis direction. The bead apex molding chamberextends in the circumferential direction, and of which circumferentialboth ends are opened. The molding process comprises a tip forming step,a middle section forming step and a joining step. The tip forming stepforms a tip portion of the bead apex rubber between front and rearshutters by flowing the unvulcanized rubber into the bead apex moldingchamber, in a closed state that the bead apex molding chamber is closedby the front and rear shutters on the front and rear sides in the beadcore rotating direction in relation to the rubber inflow port, and in arotating stopped state of the bead core. The middle section forming stepforms serially the bead apex rubber to be continuous with the tipportion by taking off the front shutter to open the front side in thebead core rotational direction and flowing the unvulcanized rubber whilerotating the bead core. The joining step joints integrally the back-endportion and the tip portion by a rubber connecting portion. In thejoining step, the bead core is stopped when the tip portion returnsagain to the bead apex molding chamber, the rear shutter is taken off toopen the rear side in the bead core rotational direction and to form aconnecting space between the back-end portion and the tip portion of thebead apex rubber, and the unvulcanized rubber is flowed into theconnecting space to form the rubber connecting portion.

In the invention according to claim 2, a bead apex rubber forming deviceforms the bead apex rubber continuously in a full circle on an outercircumferential surface of the annular bead core having a core axis. Thebead apex rubber forming device comprises a bead core holding means forholding the bead core rotatably around the core axis, a rubber extruderhaving a gear pump for extruding the unvulcanized rubber from a rubberdischarge port depending on an on-off action of the gear pump, and amolding head fixed to the anterior end of the rubber extruder. Themolding head comprises a passing space where a part of the rotating beadcore passes. The passing space comprises a bead apex molding chambersurrounded by the outer circumferential surface of the bead core passingthe passing space, a first inner wall surface of the molding head on oneside of the core axis direction, and a second inner wall surface of themolding head on the other side of the core axis direction. The bead apexmolding chamber extends in the circumferential direction, and of whichcircumferential both ends are opened. The first inner wall surface isprovided with a rubber inflow port connected with the rubber dischargeport via a rubber flow channel to flow the unvulcanized rubber from therubber extruder into the bead apex molding chamber. The molding headcomprises the front shutter, the rear shutter and a cutter. The frontshutter closes the bead apex molding chamber on the front side in thebead core rotational direction in relation to the rubber inflow port.The rear shutter closes the bead apex molding chamber on the rear sidein the bead core rotational direction in relation to the rubber inflowport. The cutter cuts the rubber portion in the rubber flow channel fromthe rubber portion in the bead apex molding chamber by crossing therubber inflow port along the first inner wall surface.

Effect of the Invention

A bead apex rubber forming method comprises a molding process to form abead apex rubber, by flowing unvulcanized rubber into a bead apexmolding chamber, directly on an outer circumferential surface of a beadcore rotating around a core axis. This molding process comprises a tipforming step to form a tip portion of the bead apex rubber, a middlesection forming step to form serially the bead apex rubber to becontinuous with the tip portion, and a joining step to joint a back-endportion and the tip portion by flowing unvulcanized rubber.

In the tip forming step, front and rear shutters close the bead apexmolding chamber on the front side and rear side in the bead corerotational direction in related to the rubber inflow port. And, in arotating stopped state of the bead core, the unvulcanized rubber isflowed into the closed bead apex molding chamber so as to form the tipportion of the bead apex rubber.

Firstly, in the tip forming step, since the bead apex molding chamber isin the closed state, the rubber inner pressure can be heightened in themolding chamber. Therefore, owing to the rubber filled up in the moldingchamber, the tip portion can be accurately made. Since the rubber innerpressure is high, the sticking force between the tip portion and thebead core is heightened, adhesion strength can be improved.

Secondly, in the middle section forming step, in a state that the frontside in the bead core rotational direction is opened by taking off thefront shutter, the unvulcanized rubber flows while the bead corerotating. This makes the bead apex rubber serially to be continuous withthe tip portion.

In the bead apex molding chamber, since the tip portion has al readybeen formed, when also the front shutter is taken off, the bead apexmolding chamber is substantially in the closed state. Therefore, therubber flowed from the rubber inflow port pushes the rubber moldingportion, which has already molded in the bead apex molding chamber,toward the front side in the bead core rotational direction, andconnecting with the rubber molding portion. At this time, the bead corecan integrally rotates with the rubber molding portion owing to thepushing force by the rubber toward the front side in the bead corerotational direction.

Finally, in the joining step, the bead core rotates substantially once,and the tip portion come back to the bead apex molding chamber, the beadcore is stopped, and the rear shutter is removed to open the rear sidein the bead core rotational direction. This forms a connecting spacebetween a back-end portion and the tip portion of the bead apex rubber.And in the connecting space, the unvulcanized rubber is flowed more.This allows integrally connect the back-end portion and the tip portionby the rubber connecting portion.

As seen from the above, the space between the tip portion and theback-end portion is filled with the flowed unvulcanized rubber andconnected in the same cross-section shape, and the bead apex rubber getsto have a substantially joint-less structure. Therefore, theconventional gap and overlapping attributed to a joint do not occur,weight dispersion is inhibited, and adhesive separation in the jointportion can be prevented.

Furthermore, the bead apex rubber is formed in a circular form inholding a high-temperature state. Thus, the shrinking and a deformationattributed to the shrinking can be inhibited by constriction in whole.And, since the bead apex rubber is integrally formed with the bead core,the bead apex rubber and the bead core can keep high adhesion strength.

And, it eliminates the need for a conventional cooling process and apasting process. Therefore, this can make a contribution by reducingnumber of processes, improving production efficiency, reducing factoryspace, and downsizing a manufacturing line and an apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

[FIG. 1] A side view showing an embodiment of a bead apex rubber formingdevice for a bead apex rubber forming method of the present invention.

[FIG. 2] A side enlarged view of a major portion of the bead apex rubberforming device.

[FIG. 3] A perspective view of the major portion of the bead apex rubberforming device.

[FIG. 4] A cross-sectional overhead view of the major portion of thebead apex rubber forming device.

[FIG. 5] A perspective view showing a bead core holding means.

[FIG. 6] (A) is a cross-sectional view of a bead apex molding chamber inthe core axis direction, and (B) is an exploded perspective viewthereof.

[FIG. 7] A front view conceptually showing a molding process.

[FIG. 8] A cross-sectional overhead view explaining a tip forming step.

[FIG. 9] A cross-sectional overhead view explaining a middle sectionforming step.

[FIG. 10] A cross-sectional overhead view explaining a joining step.

[FIG. 11] (A) is a cross-sectional view of a bead portion of a tire, and(B) is a side view of a conventional forming method of a bead apexrubber.

[FIG. 12] (A) to (E) are drawings showing some problems of theconventional bead apex rubber forming method.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will beconcretely described. FIG. 1 is a side view showing an embodiment of abead apex rubber forming device 1 (may be simply called “forming device1”).

As shown in FIG. 1, the forming device 1 comprises a bead core holdingmeans 2 for holding rotatably an annular bead core A around a core axis,a rubber extruder 4 extruding unvulcanized rubber G from a rubberdischarge port 3, and a molding head 5 fixed to a anterior end of therubber extruder 4. As shown in FIG. 3, the forming device 1 forms a beadapex rubber B in a full circle on the outer circumferential surface ofthe bead core A.

In the present embodiment, as shown in FIG. 5, the bead core holdingmeans 2 comprises a pair of parallel holding rollers 2 a, 2 a to hold aninner periphery of the bead core A. The holding rollers 2 a, 2 a isrotatably mounted on a supporting platform 6 (shown in FIGS. 1 and 2)holding the molding head 5 via a roller holder 7. The bead core A isrotatably held around the horizontal core axis in suspending andstraddled state between the holding rollers 2 a, 2 a. The bead coreholding means 2 of the present embodiment comprises plural of siderollers 2 b to keep a posture stability of the bead core A by holding aside surface of the bead core A.

The rubber extruder 4 is provided in the anterior end portion with agear pump 8, and extrudes the unvulcanized rubber G from a rubberdischarge port 9 (shown in FIG. 4) depending on an on-off action of thegear pump 8. specifically, the rubber extruder 4 of the presentembodiment comprises a rubber extruder main body 10 pushing the inputrubber G toward a opening 10H of the anterior end while kneading, andthe gear pump 8 provided with the anterior end portion of the rubberextruder main body 10. The rubber extruder main body 10 has a well-knownstructure comprising a cylinder 10 a comprising the rubber slot 10 c anda screw shaft 10 b disposed in the cylinder 10 a. Owing to the rotationof the screw shaft 10 b by the electric motor M, the rubber G isextruded with kneading from the opening 10H of the anterior end ofcylinder 10 a.

As shown in FIG. 2, the gear pump 8 is a well-known isovolumic extruder.The gear pump 8 comprises a case 11 and a pair of extrusion gears 8 adisposed in the case 11. The extrusion gears 8 a rotate in engaging oneanother with an electric motor (not shown). And the rubber G extrudedfrom the rubber extruder main body 10 is pushed from the rubberdischarge port 9 (shown in FIG. 4) of the anterior end. The case 11 ofthe present embodiment is attached to the anterior end of the rubberextruder main body 10 and supported from underneath by the supportingplatform 6.

As shown FIGS. 2, 6(A), and 6(B), the molding head 5 comprises a passingspace 12 where a part of the rotating bead core A passes in thecircumferential direction. The passing space 12 comprises a bead apexmolding chamber 15 (may be simply called “molding chamber 15”) having atriangle-shaped in cross-sectional view. The molding chamber 15 issurrounded by the outer circumferential surface As of the bead core Apassing through the passing space 12, a first inner wall surface 13 s ofthe molding head 5 on one side of the core axis direction, and a secondinner wall surface 14 s of the molding head 5 on the other side. Themolding chamber 15 extends in the circumferential direction, and theboth end portions thereof are open.

Specifically, the molding head 5 of the present embodiment comprises ahead main body 13 fixed on the side of the gear pump 8, and a coverplate 14 kept on the head main body 13 with a holding means 17. Anexterior surface 13A of the head main body 13 forms the first inner wallsurface 13 s of the molding chamber 15. An internal face 14A of thecover plate 14 forms the second inner wall surface 14 s of the moldingchamber 15. Technically, the internal face 14A of the cover plate 14 ofthe present embodiment comprises a contacting surface 14A1 positioned onthe exterior surface 13A of the head main body 13, and a sloping surface14A2 continuing into the contacting surface 14A1. And the slopingsurface 14A2 forms the second inner wall surface 14 s. The cover plate14 can change its positions between a closed state Y1 for forming themolding chamber 15 and an opened state Y2 for opening the moldingchamber 15 by the holding means 17 such as using cylinder. In the openedstate Y2, a takeoff of the core assembled body from the molding chamber15 and a mounting of a next bead core A onto the molding chamber 15 areconducted.

In the first inner wall surface 13 s of the molding head 5, a rubberinflow port 19 opens. As shown in FIGS. 4 and 8, the rubber inflow port19 continues into the rubber discharge port 9 via a rubber flow channel18 and let flow the rubber G input from the rubber extruder 4 into themolding chamber 15. The rubber flow channel 18 comprises a taperedsqueezing channel 18 a having a cross-sectional area gradually reducedtoward the front, and a parallel channel 18 b extending from thesqueezing channel 18 a to the rubber inflow port 19 and having asubstantially constant cross-sectional area. The parallel channel 18 binclines to the front side F1 in the bead core rotational direction.

The molding head 5 comprises a front shutter 20 to close the moldingchamber 15 on the front side F1 in the bead core rotational direction inrelation to the rubber inflow port 19, a rear shutter 21 to close themolding chamber 15 on the rear side F2 in the bead core rotationaldirection in relation to the rubber inflow port 19. In the presentembodiment, in a circumferential front of the molding head 5, a guidinggrove 22 extends up and down. The front shutter 20 is movable up anddown along the guiding groove 22. Therefore the molding chamber 15 canbe opened and closed the front side F1 in the bead core rotationaldirection in relation to the rubber inflow port 19.

The head main body 13 comprises a guiding groove 23 extending at anangle toward the front side F1 in the bead core rotational direction andintersecting with the molding chamber 15. The rear shutter 21 is movableback and forth along the guiding groove 23. In a forward movement, therear shutter 21 traverses the molding chamber 15, and its anterior endsurface 21 s thickly contacts with the second inner wall surface 14 s.Thus the rear shutter 21 can close the molding chamber 15 the rear sideF2 in the bead core rotational direction in relation to the rubberinflow port 19. In the posterior movement of the rear shutter 21, themolding chamber 15 is opened. It is preferable to open-and-close therear shutter 21 at a position near the rubber inflow port 19 in ajoining step described below for letting flow the unvulcanized rubber Ginto a connecting space J. Therefore, a distance L (shown in FIG. 8)between the guiding groove 23 and the rubber inflow port 19 is set to benot more than 1 mm. For the same purpose, an angle θ1 of the guidinggroove 23 with respect to the circumferential direction is alsopreferably set to be smaller than an angle θ2 of the parallel channel 18b with respect to the circumferential direction.

The molding head 5 comprises a cutter 25. The cutter 25 cuts across therubber inflow port 19 along the first inner wall surface 13 s. And thecutter 25 cuts off the rubber in the rubber flow channel 18 from therubber in the molding chamber 15. The cutter 25 of the presentembodiment can move back and forth along the guiding groove 26 formed inthe first inner wall surface 13 s. The rubber inflow port 19 opens in abottom face of the guiding groove 26. Meanwhile an item 30 shown in FIG.4 indicates a driving means for driving the cutter 25, and a cylinder isemployed in the present embodiment. An item 31 indicates a driving meansof the rear shutter 21, and a gear-rack structure is employed in thepresent embodiment. The front shutter 20 is derived by a driving means(not shown) such as the cylinder.

Next, a bead apex rubber forming method (may be simply called “formingmethod”) will be explained with the forming device 1.

As shown in FIG. 7, the forming method of the present embodimentcomprises a molding process P to form the bead apex rubber B integrallyon an outer circumferential surface As of a rotating bead core A byletting flow the unvulcanized rubber G from the rubber inflow port 19into the molding chamber 15.

The molding process P, as shown in FIG. 7, comprises a tip forming stepP1 to form a tip portion Bf of the bead apex rubber B, a middle sectionforming step P2 to form serially the bead apex rubber B so as to becontinuous with the tip portion Bf, and a joining step P3 to connectintegrally the back-end portion Br with the tip portion Bf by flowingthe unvulcanized rubber in the connecting space J between the back-endportion Br and the tip portion Bf.

FIGS. 8 to 10 are overhead views of the molding chamber 15, the beadcore A is abbreviated for convenience sake. As shown in FIG. 8, in thetip forming step P1, the front and rear shutters 20, 21 close themolding chamber 15 on the front side F1 and the rear side F2 in the beadcore rotational direction in relation to the rubber inflow port 19. In arotating stopped state of the bead core A, the molding chamber 15 in theclosed state is filled with the poured unvulcanized rubber G. Thus thetip portion Bf of the bead apex rubber B is formed between the front andrear shutters 20, 21.

In this time, the molding chamber 15 gets into the closed state by thefront and rear shutters 20, 21, a rubber inner pressure can be raised inthe molding chamber 15. In consequence, the tip portion Bf can be formedaccurately. And since the rubber inner pressure is high, the stickingforce between the tip portion Bf and the bead core A is heightened, andthe adhesion strength can be improved. Meanwhile, the inflow-and-stopand the volume of flow of the rubber G is controlled with the on-and-offof the gear pump 8.

As shown in FIG. 9, in the middle section forming step P2, the frontshutter 20 is taken off, and the front side F1 in the bead corerotational direction is opened, and the unvulcanized rubber G is flowedfrom the rubber inflow port 19 while rotating the bead core A. Thisconnects with the tip portion Bf to form the bead apex rubber Bserially.

In the molding chamber 15, since the tip portion Bf has already beenformed, even if the front shutter 20 is taken off, the molding chamber15 is substantially in the closed state. Therefore, the rubber G flowedfrom the rubber inflow port 19 pushes the rubber molding portion, whichhas been already formed in the molding chamber 15, toward the front sideF1 in the bead core rotational direction and connects with the rubbermolding portion to form the bead apex rubber B serially. At this time,the bead core A can integrally rotates with the rubber molding portionowing to the pushing force by the rubber G toward the front side F1 inthe bead core rotational direction. That is to say, the forming device 1of the present embodiment needs no motor and the like to drive the beadcore A, but the pushing force of the rubber G rotates automatically.Therefore, the structure of the bead core holding means 2 can besimplified.

In the joining step P3, when the bead core A substantially goes aroundand the tip portion Bf comes back to the molding chamber 15, therotation of the bead core A gets stopped (FIG. 10(A)). This stopping canbe conducted with the stop of flowing of the rubber G from the rubberinflow port 19 by the gear pump 8. And, supplementary, brake means canbe employed. Subsequently, the rear shutter 21 sets back to open therear side F2 in the bead core rotational direction (FIG. 10(B)). Thisforms a connecting space J between the back-end portion Br and the tipportion Bf of the bead apex rubber B. In the present embodiment, since abackward amount of the rear shutter 21 is large, the cutter 25 iscarried forward the position of the back-end portion Br so as to thecutter 25 forms a first inner wall surface 13 s in the connecting spaceJ (FIG. 10(C)). However, the first inner wall surface 13 s in theconnecting space J can be also made by carry backward the anterior endsurface 21 s of the rear shutter 21 to the same plane of the first innerwall surface 13 s.

After forming the connecting space J, by putting the gear pump 8 intopractice, the rubber G can be flowed into the connecting space J. Theback-end portion Br and the tip portion Bf are integrally connected bythe rubber connecting portion Bm (FIG. 10(D)). Since the rubber inflowport 19 is positioned near the rear shutter 21, and since the rearshutter 21 inclines toward the front side F1 in the bead core rotationaldirection, in the back-end portion Br, the connecting side with therubber inflow port 19 takes the form of having an acute angle.Therefore, the rubber G from the rubber inflow port 19 can flow easilyfrom the acute angle part into the connecting space J.

In the present embodiment, after forming the rubber connecting portionBm, a cutoff step P4 is conducted (FIG. 10(E)). In the cutoff step P4,the cutter 25 carries forward to across the rubber inflow port 19 alongthe first inner wall surface 13 s. In doing so, the bead apex rubber Bis cut off from the rubber portion in the rubber flow channel 18. Therubber inflow port 19 has a small diameter. Therefore, the rubber can becut off not using the cutter 25 but strain at the time of taking thecore assembled body off from the molding chamber 15.

As presented above, in the molding process P, the tip portion Bf and theback-end portion Br can also connected in the same cross-sectional shapewith the flow of the unvulcanized rubber. Thus, the bead apex rubber Bis formed in a substantially joint-less form. Therefore, theconventional gap and overlapping attributed to a joint do not occur, theweight dispersion is inhibited, and adhesive separation in the jointportion can be prevented.

Although the especially preferred embodiments of the present inventionhave been described in detail, the invention is not limited to theabove-mentioned specific embodiments, and various modifications can bemade.

EXPLANATION OF THE REFERENCE

-   1 Bead apex rubber forming device-   2 Bead core holding means-   3 Rubber discharge port-   4 Rubber extruder-   5 Molding head-   8 Gear pump-   12 Passing space-   13 s First inner wall surface-   14 s Second inner wall surface-   15 Bead apex molding chamber-   18 Rubber flow channel-   19 Rubber inflow port-   20 Front shutter-   21 Rear shutter-   25 Cutter-   A Bead core-   As Outer circumferential surface-   B Bead apex rubber-   Bf Tip portion-   Bm Rubber connecting portion-   Br Back-end portion-   G Unvulcanized rubber-   J Connecting space-   P Molding process-   P1 Tip forming step-   P2 Middle section forming step-   P3 Joining step

1. A bead apex rubber forming method to form the bead apex rubbercontinuously in a full circle on an outer circumferential surface of theannular bead core having a core axis, wherein the method comprises amolding process to form the bead apex rubber integrally on the outercircumferential surface of the bead core rotating around the core axisby flowing unvulcanized rubber from a rubber inflow port positioned in afirst inner wall surface of a molding head into a bead apex moldingchamber, the bead apex molding chamber is surrounded by the outercircumferential surface of the bead core, a first inner wall surface ofthe molding head on one side of the core axis direction, and a secondinner wall surface of the molding head on the other side of the coreaxis direction, and the bead apex molding chamber extends in thecircumferential direction, and of which circumferential both ends areopened, wherein the molding process comprises a tip forming step to forma tip portion of the bead apex rubber between front and rear shutters byflowing the unvulcanized rubber into the bead apex molding chamber, in aclosed state that the bead apex molding chamber is closed by the frontand rear shutters on the front and rear sides in the bead core rotatingdirection in relation to the rubber inflow port, and in a rotatingstopped state of the bead core, a middle section forming step to formserially the bead apex rubber to be continuous with the tip portion bytaking off the front shutter to open the front side in the bead corerotational direction and flowing the unvulcanized rubber while rotatingthe bead core, and a joining step to joint integrally the back-endportion and the tip portion by a rubber connecting portion, and wherein,in the joining step, the bead core is stopped when the tip portionreturns again to the bead apex molding chamber, the rear shutter istaken off to open the rear side in the bead core rotational directionand to form a connecting space between the back-end portion and the tipportion of the bead apex rubber, and the unvulcanized rubber is flowedinto the connecting space to form the rubber connecting portion.
 2. Abead apex rubber forming device to form the bead apex rubbercontinuously in a full circle on an outer circumferential surface of theannular bead core having a core axis, wherein the bead apex rubberforming device comprises a bead core holding means for holding the beadcore rotatably around the core axis, a rubber extruder having a gearpump for extruding the unvulcanized rubber from a rubber discharge portdepending on an on-off action of the gear pump, and a molding head fixedto the anterior end of the rubber extruder, the molding head comprises apassing space where a part of the rotating bead core passes, the passingspace comprises a bead apex molding chamber surrounded by the outercircumferential surface of the bead core passing the passing space, afirst inner wall surface of the molding head on one side of the coreaxis direction, and a second inner wall surface of the molding head onthe other side of the core axis direction, the bead apex molding chamberextends in the circumferential direction, and of which circumferentialboth ends are opened, the first inner wall surface is provided with arubber inflow port connected with the rubber discharge port via a rubberflow channel to flow the unvulcanized rubber from the rubber extruderinto the bead apex molding chamber, and the molding head comprises thefront shutter to close the bead apex molding chamber on the front sidein the bead core rotational direction in relation to the rubber inflowport, the rear shutter to close the bead apex molding chamber on therear side in the bead core rotational direction in relation to therubber inflow port, and a cutter to cut the rubber portion in the rubberflow channel from the rubber portion in the bead apex molding chamber bycrossing the rubber inflow port along the first inner wall surface.